feat: add existing for setnx2

bucket.go

@@ -59,12 +59,12 @@ func (b *bucket[T]) setnx(key string, value T, duration time.Duration, track boo
 	return newItem
 }
 
-func (b *bucket[T]) setnx2(key string, f func() T, duration time.Duration, track bool) *Item[T] {
+func (b *bucket[T]) setnx2(key string, f func() T, duration time.Duration, track bool) (*Item[T], bool) {
 	b.RLock()
 	item := b.lookup[key]
 	b.RUnlock()
 	if item != nil {
-		return item
+		return item, true
 	}
 
 	b.Lock()
@@ -73,14 +73,14 @@ func (b *bucket[T]) setnx2(key string, f func() T, duration time.Duration, track
 	// check again under write lock
 	item = b.lookup[key]
 	if item != nil {
-		return item
+		return item, true
 	}
 
 	expires := time.Now().Add(duration).UnixNano()
 	newItem := newItem(key, f(), expires, track)
 
 	b.lookup[key] = newItem
-	return newItem
+	return newItem, false
 }
 
 func (b *bucket[T]) set(key string, value T, duration time.Duration, track bool) (*Item[T], *Item[T]) {

cache.go

@@ -126,8 +126,17 @@ func (c *Cache[T]) Setnx(key string, value T, duration time.Duration) {
 
 // Setnx2 set the value in the cache for the specified duration if not exists
 func (c *Cache[T]) Setnx2(key string, f func() T, duration time.Duration) *Item[T] {
-	item := c.bucket(key).setnx2(key, f, duration, false)
+	item, existing := c.bucket(key).setnx2(key, f, duration, false)
+	// consistent with Get
+	if existing && !item.Expired() {
+		select {
+		case c.promotables <- item:
+		default:
+		}
+		// consistent with set
+	} else if !existing {
 		c.promotables <- item
+	}
 	return item
 }